The present invention is directed to a system for controlling water flow ultrasonically.
Water has taken its place with other commodities as an object of conservation. Accordingly, numerous devices have been proposed to aid in the conservation effort. Among the most important devices for domestic use are those for restricting unnecessary water flow. For instance, shower heads that decrease the volume flow of water while increasing its velocity to maintain the effectiveness of the water flow can reduce water usage during showers to a fraction of previous levels.
Another cause of wasted water is the flow of water during periods when it is not actually being used. For instance, when dishes are being rinsed, it is not uncommon for the user to allow the water to run in a steady stream even though the rinsing only occurs intermittently. This is largely a result of the inconvenience of turning the water on and off at frequent intervals.
Accordingly, devices have been proposed that automatically sense the proximity of an object to a faucet and operate the faucet in response to the proximity. The intended result is for the water to flow only when an object is actually below the faucet. In addition to saving water, such devices eliminate the need to operate a valve manually. Such an arrangement can be beneficial to people whose hands are full, who are handicapped, or who, like surgeons, cannot touch nonsterile objects after washing.
The devices heretofore proposed have employed optical or electromagnetic sensing means, which, although possibly practicable, present certain design complexities and practical difficulties. In the case of the electromagnetic devices, there is a lack of directivity in the sensors, and this presents obvious difficulties in the dishwashing and rinsing situation. Optical devices, on the other hand, can be quite directive. But it is difficult to restrict their sensing ranges to prescribed distances.
Other problems arise in some types of sensing arrangements. For instance, when Doppler-type sensors are used with stainless-steel sinks, flow can be triggered unnecessarily when shocks and sound from positions remote from the area of interest propagate into the target region because of the propagation characteristics of the stainless-steel sink.
Also, adoption of proximity-sensing devices for domestic use is inhibited by the need to run wires to the faucet. Although the power for such devices would ordinarily be supplied at safe, low voltages, the association of danger in the mind of the user with the combination of water and electricity might make him reluctant to adopt such a device.
It is accordingly an object of the present invention to provide a means of object sensing that is less prone to the design and utilization difficulties that beset optical and electromagnetic devices.
An object of some of the aspects of the present invention is to avoid difficulties presented by Doppler-type devices.
An object of other aspects of the present invention is to avoid the pyschological barrier caused by the use of visible electrical connections.